Changes between Version 2 and Version 3 of averaging


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Timestamp:
Jan 21, 2012, 9:21:38 AM (13 years ago)
Author:
bpt
Comment:

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  • averaging

    v2 v3  
    39395. If an error is thrown during the averaging process it is most likely that an image or template named in the list does not exist or is corrupted.
    4040
     41== Averaging options ==
     42
     43The options which affect the average construction are mostly on the Average menu e.g.
     44
     451) Texture Options
     46
     47  - None (just averages pixel colours),
     48
     49  - wavelet magnitude (amplifies local edge sizes a different scales to match the same measure across the group,
     50
     51  - wavelet MRF (tries to build up the most probable texture patterns by sampling from the group)
     52
     532) Recalculating the average template (rather than loading one in),
     54
     553) auto resizing the average template (tries to scale and shift the average template to make as large as possible within the bounds of the image on the right),
     56
     574) shape normalisation options
     58
     59    - none (just averages the point positions),
     60
     61    - two point (rotates, shifts and scales each template around two points to line up with the template on the right before averaging the templates), 
     62
     63    - three points (aligns 3 points, which allows shearing (affine transform)),
     64
     65    - Full (Procrustes) (aligns each template to the average in order to minimise the sum of squared distances of each point from the same point in the average),
     66
     675) warping options
     68
     69   - Multiscale - a simple non-linear interpolation, reasonably efficient even for lots of sample points
     70
     71   - Linear - triangulates the delineation points and linearly interpolates over the triangles
     72
     73   - thin-plate spline - an energy minimising spline, mathematically the best but slow for lots of points.
     74
     75  - overlap control - tries to prevent the warp folding, by scaling each partial warp until it doesn't fold and concatenating the non-folding warps together.
     76
     77As a guide the following settings could be selected: either none or wavelet magnitude on the texture, recalculate the average, don't auto resize, full (procrustes) shape normalisation, multiscale warping.
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